Eyelid Crease Anatomy
How the different types of East Asian eyelids work
When the skin of East Asian single eyelids opens, it follows a micro-crease that’s located too close to the upper eyelashes, resulting in a lack of internal pressure for the inner eyelid layers to move as a single unit. So, when the eyelid opens, the underlying muscle and tarsal plate move independently from the external skin. This makes the eyelid skin near the upper eyelashes to initially roll inwards, instead of clumping together so that the upper skin can drape over on top as in a double eyelid.
When the skin of East Asian double eyelids opens, as the eyelid muscles retract (orbicularis muscle, levator aponeurosis), a properly located crease ― supported by a dominant skin tension line ― applies internal pressure to the layers of the upper eyelid (upper eyelid skin, subcutaneous fat, underlying muscle tissue, tarsal plate). This pressure causes the eyelid layers to ‘sandwich’ together, moving upwards as a single unit, and enabling eyelid skin located above it to drape over, forming the double eyelid.
Skin Crease Geometry
The Relationship between Eyeballs & Face-Shapes
Adult human eyeballs do not vary in statistically significant dimensions regardless of gender, age, and ethnic background.
In contrary, the size of adult human skulls ― which contributes largely to one's face-shape ― do vary in statistically significant dimensions correlated with gender, age, and ethnic background.
Depending on one’s particular face-shape, how the skin wraps around the facial subunits of the periorbital area (spherical eyeball shape), determines the location of skin tension lines that may either support a double eyelid crease to be made or an ideal crease to be reinforced.
Relaxed Skin Tension Lines (RSTL)
The Kraissl's lines that run perpendicular to the action of muscles
Relaxed skin tension lines are produced in living subjects by positioning the body so that the skin is relaxed, and then gently pinching the skin to reveal a crease.
When the topographical skin surface area expands and has a faster growth rate than the underlying biological layers, the skin will crease.
As the crease is aligned with the dominant skin tension line that corresponds to the activation of the levator aponeurosis eyelid muscle, it will form more readily every time the eyelid opens.
Eyelid Crease Stimulation
How mechanical stress loads are exerted to the skin
The fTape keeps the eyelid stretched (1) while covering the extended-state eyelid skin from the eyelid margin all the way to, and thus targeting, the dominant skin tension line (2). Various sizes are available for a custom tailored fit.
The nTape's upper body grips the upper skin (3) in preparation to be lowered. It compresses the ideal eyelid crease (4) and it's non-adhesive midsection prevents eyelashes from sticking onto it (5).
When the nTape legs are lowered and adhered onto the lower eyelid (6), the pulling force transfers to the nTape's upper body. This is felt by an increased stretching sensation necessary to trigger mechanotransduction pathways in the skin for gradual but long-term changes.
It's more than just skin deep
Eyelids are the thinnest skin on the human body (0.5 mm). They are one of the first areas to show signs of aging, which include creases.
Although thin, the eyelids are comprised of different layers including fat, muscle, and skin. These vary in their behaviour by the influence of hormonal changes in the body throughout the day.
These changes below the skin can make the entire eyelid swollen, giving the developing ideal crease a challenge to form. Understanding how to reduce swelling in the eyelids will accelerate your crease's progress to full strength.
Eyelid Water Retention
Factors that causes the eyelids to swell
Accelerating your crease's progress to full strength means you're actively
avoiding the following daily life situations that causes the eyelids to swell:
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